Process of purifying water.



UNITED STATES PATENT- 1 FFICE.

PROCESS OF PURIFYING WATER SPECIFIGATIQN forming part Of Letters PatentNo. 677,668, dated July 2, 1901. Application filed December 15, 1900.Serial No. 39,990. (No specimens.)

To all 1072,0772, it may concern.-

Be it known that I, CHARLES HERSGHEL KOYL, a citizen of the UnitedStates, and a resident of New York city, in the county and State of NewYork, havev invented a certain new and Improved Process for thePurification of ater, of which the-following is a specification.

In Letters Patent- No. 653,008, granted to me July 3, 1900, I havedescribed and claimed a process of treating water for purposes ofpurification, which consists in first preparing the water byintimatelymixing with it sodium hydroxid or sodium hydrate and then adding to thethus-prepared water ferrous sulfate (or. aluminium sulfate.) Myinvention is an improvement on said patented process. That process isentirely satisfactory for the treatment of most waters; but there aresome waters which contain in solution free carbonicacid gas, and theprocess when used in connection with these waters does not give suchsatisfactory results unless the sodium hydrate is used in excess, forthe reason that the free carbonic-acid gas in the water unites with thesodium hydrate usedin the process to form sodium bicarbonate, and thesodium bicarbonate reacts with the subsequently-added ferrous sulfate toform soluble bicarbonate of iron. The presence of sodium bicarbonate isobjectionable,because it remains dissolved in the water and has atendency to. make boilerwaters foam. The presence of soluble bicarbonateof iron is objectionable, because upon long standing it loses part orall of its carbonic-acid gas (00,) and is deposited as basic ferriccarbonate or as the hydrated oxid of H011.

It is the object of my improvement to extract the free carbonic-acid gasfrom such waters before it has the opportunity to act upon the sodiumhydrate and at the same time to preserve the proper amount of sodiumhydrate to combine with the ferrous sulfate, as in my said patentedprocess.

I have found that the free carbonic-acid gas can be extracted from thewater to be treated by the action oflime-water, [Oa(OH) Sodium hydratecan be produced by the union of lime-water with its equivalent of sodiumcarbonate. I avail myself of these facts to effectuate the object I havein View by addtroduced to produce in the water the amount of sodiumhydrate needed to combine with the ferrous sulfate when the latter isintroduced to produce the flocoulent precipitate of my patented process.It is this feature that characterizes my improvement.

In carrying out myimprovementI proceed as follows: I provide the threereagents-dime water, sodium carbonate, and ferrous sulfate, (or theequivalent, aluminium sulfate.) I first thoroughly mix with the rawwater a definite amount of lime-water. Then I add and thoroughly mixwith the water a definite amount of sodium carbonate. Then I add andthoroughly mix with the water a definite amount of ferrous sulfate oraluminium sulfate. This succession of independent mixings I accomplishby means of the apparatus shown in my Patents Nos.653,009 and 653,010,

of July 3, 1900, or by any other suitable means. The reactions whichtake place are as follows: Upon introduction of the limewater the freecarbonic-acid gas (00 in the raw water unites with its equivalent oflimewater [Oa(OH) to form calcium carbonate, (OaGO which is insolubleand settles as a precipitate. Then when the sodium carbonate is addedthe balance of the lime-water [Oa(OH) goes on to meet its equivalent ofsodium carbonate, (Na CO with which it combines to form calciumcarbonate (CaOO and sodium hydrate, (NaOIL) the former being insolubleand settling as a precipitate, the latter remaining in solution in thewater. Finally, when the ferrous sulfate is introduced the sodiumhydrate (NaOH) thus formed goes on with the water, to meet itsequivalent of ferrous sulfate (FeSO or aluminium sulfate, with which itcombines to form sodium sulfate (Na SO and ferrous hydrate [Fe(OH) oraluminium hydrate, the sodium sulfate remaining dissolved in the waterand the ferrous hydrate or aluminium hydrate being insoluble andsettling as a procipitate. The ferrous hydrate absorbs oxygen rapidlyfrom the water, and is thus converted into insoluble ferric hydrate,which (or aluminium hydrate, if aluminium sulfate be used) is theflocculent precipitate for the production of which the aforesaidpatented process is designed.

The proportions as well as the absolute amounts of the chemical reagentsused will of course depend largely upon the quality and character of theparticular water to be treated and will vary as those Waters vary fromone another. By Way of example I may say that in the case of one waterwhich Ihave successfully treated I use per gallon of water: calciumhydrate [Ca(OH) as lime-water, 2.775 grains; sodium carbonate, (NaCO1.324: grains; crystallized ferrous sulfate, (FeSO 7H O,) 3.500 grains.

Having described my improvement and the ing to the thusprepared waterferrous sulfate, substantially as and for the purposes horeinbefore setforth.

In testimony whereof I have hereunto set my hand this 14th day ofDecember, 1900. CHARLES HERSOHEL KOYL. Witnesses:

HENRY BEYER, HARRY H. SU'rno.

